Dynamic balance is one of the important factors for tire production. When a tire has poor dynamic balance, its performance is worsened due to the centrifugal force generated being too big or too small. An improperly installed tire can lead to unpredictable, unavoidable accidents. Therefore there is an great need to be able to measure the dynamic balance of tires on a production line, anywhere from spot-checking to checking 100% of tires, for all different specifications. There is a great need for a machine that automatically inflates tires and automatically measures their dynamic balance with high efficiency. Before such automated measurement of dynamic balance can take place, it is necessary to know the tire specification and the 3D parameters of the tire need to be known. Thus it is necessary to measure the 3D parameters of a tire—including the section width, inner radius and outer radius—to obtain the specification of the tire so as to provide known parameters for the measurement of dynamic balance. In addition, during the procedure of the tire manufacturing, many factors such as rubber quality and controlling parameters of squeezing and equipment conditions, can lead to malformation of a tire, causing incorrect section width, inner radius or outer radius. If it were possible to measure such 3D parameters in an automated way during manufacture, then manufacturing equipment could be automatically adjusted accordingly, and it would be possible to decrease the quantities of waste or under-finished tires. It will be appreciated that the ability to measure 3D parameters of tires plays an important role in the developing and manufacturing of high-performance tires, and such a measurement ability has been widely applied to quality control in tire manufacturing.
Recently, there two methods have been developed for measuring 3D parameters of a tire—one is manual measurement and the other is photoelectrical measurement. The manual measurement is unsuitable for 100% on-line inspection in situ because it has many disadvantages; such a measurement is time-consuming, has low efficiency, and has poor accuracy. The photoelectrical measurement has two concrete methods. One method utilizes at least two laser position sensors to perform thickness and width measurement. The other method is based on casting a shadow, for example utilizing optoCONTROL sensors produced by MICRO-EPSILON MESSTECHNIK GmbH & Co. KG to measure the parameters of a tire. Each set of photoelectric equipment used is only able to measure one parameter. This means that more than one set of equipment is needed to be able to measure all parameters of a tire. Moreover, the photoelectrical measurement methods presented above have a narrow measuring range, the apparatus is expensive, and the setup is elaborate. Yet another drawback is that such systems require that the tire be static (unmoving) at the time of the measurement, and the accurate center of the tire must be known. This makes the mechanical construction of such a system very complicated. There is thus a great need for a system for measuring the 3D parameters of a tire (for example, section width, inner radius, and outer radius) that does not require that the tire be motionless, that does not need accurate knowledge of the center of the tire, that is not time-consuming, that is efficient, that is accurate, that does not need to be replicated for each parameter to be measured, that has a wide measuring range, that is not expensive, that is not too big, that does not have a complicated mechanical constructions, and the setup of which is not elaborate.